/*
 * CCVisu is a tool for visual graph clustering
 * and general force-directed graph layout.
 * This file is part of CCVisu.
 *
 * Copyright (C) 2005-2011  Dirk Beyer
 *
 * CCVisu is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public License
 * as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * CCVisu is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with CCVisu; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * Please find the GNU Lesser General Public License in file
 * license_lgpl.txt or http://www.gnu.org/licenses/lgpl.txt
 *
 * Dirk Beyer    (firstname.lastname@uni-passau.de)
 * University of Passau, Bavaria, Germany
 */
package org.sosy_lab.ccvisu.readers;

import java.io.BufferedReader;
import java.io.IOException;
import java.util.logging.Level;

import org.sosy_lab.ccvisu.graph.Relation;
import org.sosy_lab.common.LogManager;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;
import org.xml.sax.XMLReader;
import org.xml.sax.helpers.DefaultHandler;
import org.xml.sax.helpers.XMLReaderFactory;

/**
 * Reader for XML files.
 */
public abstract class ReaderDataGraphXML extends ReaderDataGraph {

  InputFormat inputFormat;

  /**
   * Constructor.
   * @param reader          Stream reader object.
   */
  public ReaderDataGraphXML(LogManager logger, BufferedReader reader,
      InputFormat inputFormat) {

    super(logger, reader);
    assert(inputFormat != null);

    this.inputFormat = inputFormat;
  }

  /**
   * Reads the tuples (edges of a graph) in XML format from stream reader
   * <code>reader</code>, and stores them in a <code>Relation</code>.
   * @return Relation, which is a list of string tuples.
   */
  @Override
  protected Relation readTuples() {
    // This is where we store the relations.
    Relation relation = new Relation();

    try {
      // Initialize xmlReader.
      XMLReader xmlReader = XMLReaderFactory.createXMLReader();
      DefaultHandler fileHandler = createFileHandler(relation);

      xmlReader.setContentHandler(fileHandler);
      xmlReader.setErrorHandler(fileHandler);

      // Parse input file.
      xmlReader.parse(new InputSource(reader));
    } catch (SAXException e) {
      logger.logUserException(Level.WARNING, e,
          "Runtime error: A SAX-error occured.");
    } catch (IOException e) {
      logger.logUserException(Level.SEVERE, e,
          "Runtime error: Error while opening a file.");
      System.exit(1);
    }

    return relation;
  }

  protected abstract DefaultHandler createFileHandler(Relation relation);
}
